This invention relates generally to an electrical switch. More particularly, the invention relates to a continuous sheet which comprises a sandwich of two electrically conductive layers separated by electrical insulation. Any rupture of the sheet, or discontinuity in the insulation, causes the conductors to contact each other and to complete an electrical circuit in which the conductors may be connected. The present invention is particularly, though not exclusively, useful as a switch for electrically detonating certain mulitary land mines, for detecting damage to predefined surfaces, and for sensing the penetration of an identified barrier.